Improvement in screws



Mw; wir i @r '1. 5b 5mm' @aient i (time.

v tlmtml CARL BOOKING, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO HIMSELF AND COATES WALTON, OF THE SAME PLACE.

Leners Patent No. 88,539, ma April e, 1869.

IMPROVEMENT IN SCREWS.

To all whom lit may concern.-

Be it known that LGARL BocKING, of Philadelphia, in the county of Philadelphia, and State of Pennsylvania, have invented certain new and useful Improvements in Tocci-Screws; and I do hereby declare that the following is a sufficiently full, clear, and exact description thereof, to enable one skilled in the art to which my said invention appertans, to make and carry it into etiect, reference being had to the accompanying drawings, which are made a part of this specitication, and in which- Figure l is an elevation of my improved screw, and

Figure 2, an inverted plan View thereof.

My invention relates to a novel construction of screw, whereby ease of introduction and strength are'obtained in a much greater degree than in any other screw with which I am acquainted.

4 I construct my screw of iron, Vor other suitable metal, with a head, A, of any approved form, and its core, B, of equal diaineter,.f'1'om thelcwer side of said head to the commencement of the point C, of equal diameter throughout, and surround said core its entire length with afspiral thread, D, divided longitudinally of the core ,at one or more points, or at irregular intervals, hy nicks, or grooves, el, which enable the thread to cut through the wood, as it is screwed in, and thus greatly lessen the power requisite to drive it.

The point C may have threeor more sides, and be of any desired length to render its introduction easy.

Its sides c are concave, so as. to render its angles c more acute; the action of said 'point C beingl to cut a hole ofthe same diameter as the core B, for its reception.

Having thus described my invention, y

What I claim as new therein, and desire to secure byLetters Patent, is

The angular point C, with its cutting-edges c', in combination with a wood-screw, substantially as de scribed.

To the above specification of my improvement in wood-screws, I have signed my hand, this 24th day of'` April, A. D. 1868.

CARL BOOKDT G. Witnesses THos. R. BROWN, .JULIUS F. GRAF. 

